1. Field of the Invention
The invention relates to a method to identify a human tumor which is insensitive or sensitive with a view to an administration of capecitabine, if applicable in combination with Docetaxel or Paclitaxel or the humanized antibody Herceptin® (Herceptin® is a registered trademark of Genentech, Inc., for pharmaceutical preparations for the treatment of cancer) or COX-2 inhibitors or VEGF inhibitors, preferably to identify the insensitivity or sensitivity of a metastatic carcinoma of the large intestine or the breast or another solid tumor, as well as a test kit for the determination of such an insensitivity or sensitivity. Fields of application of the invention are the pharmaceutical industry and bio-sciences: biology, biochemistry, biotechnology, medicine and medicinal technology.
2. Background of the Art
The treatment of metastatic tumors is a great challenge for oncologists. For example, 30-40% of all patients with breast cancer in western countries develop a metastatic mamma carcinoma.
Capecitabine (IUPAC name: Pentyl[1-(3,4-dihydroxy-5-methyl-tetrahydrofuran-2-yl)-5-fluoro-2-oxo-1H-pyrimidin-4-yl]aminomethanoat) is a chemotherapeutic which is regularly used in the treatment of tumors of the breast and the intestines or other solid metastatic tumors.
Capecitabine is converted in the body, finally preferably in the tumor, to form the compound 5-Fluorouracil (5-FU). In cell division, 5-FU is integrated into the DNA instead of Cytosin and Thymin as a result of its structural similarity with them. The DNA formed in this context is not functional.
Fluoropyrimidine in Therapy of a Metastatic Mamma Carcinoma
In 1987, Hansen reported for the first time on the use of a therapy with continuous administration of low-dose 5-FU in patients with highly intensive previous treatment with progressive mamma carcinoma (Hansen et al., 1987). Of 25 patients, 8 achieved an objective reaction. Toxicities such as hand and foot syndrome, mucositis, diarrhea were remedied by a short-term interruption of the therapy or a reduction of the dose. These results were repeatedly confirmed by Jabboury 1989, Huan 1989 and by Hansen 1991.
However, long-term infusions are technically complicated, expensive, work-intensive and above all uncomfortable for patients and additionally strained by complications of the central nervous catheter. Oral administration of a fluoropyrimidine on the other hand means an elegant method of imitating the effective mechanism of the protracted or 5-FU long-term infusion.
Capecitabine is an oral fluorpyrimidine carbamate. Capecitabine itself does not have a cytotoxic effect, but is converted by three enzymatic steps, mainly in the tumor, to form the active cytotoxic metabolite Fluorouracil (5-FU). Fluorouracil belongs to the group of the antimetabolites, as a pyrimidine antagonist it competes with the actual substrate and leads to an inhibition of the nucleic acid synthesis. Integration of 5-FU instead of Uracil leads to an inhibition of the RNA and protein synthesis. As a result of a blockade of the methylization of desoxyuridylic acid, there is formation of thymidylic acid, as a result of which the synthesis of the DNA is additionally influenced. The effect of the DNA and RNA deprivation most strongly affects the cells which proliferate more quickly and metabolize capecitabine more quickly to form 5-FU.
After oral absorption, capecitabine is firstly metabolized to 5′-desoxy-5-fluorcytidin (5′DFCR) with the help of hepatic carboxylesterases, the former being converted into 5′-desoxy-5-fluoruridin (5′-DFUR) by cytidin desaminase, which is mainly located in the liver and the tumor tissue (FIG. 1). Thereafter, 5′DFUR is catalytically activated with the help of the thymidine phosphorylase (TP), mainly in the tumor (Ishitsuka et al., 1995). Thymidine phosphorylase, also under the name “Tumor Associated Angiogenesis Factor”, mainly exists in high concentrations in malign cells. Matching its expression in the tumor, a tumoral and a peritumoral fraction can be distinguished. The peritumoral fraction induces the formation of VEGF (Vascular Endothelial Growth Factor) in the healthy cells surrounding the tumor (Nicholas S. Brown et al.: Thymidine Phosphorylase Induces Carcinoma Cell Oxidative Stress and Promotes Secretion of Angiogenic Factors. Cancer Research 60 (2000) 6298-6302), which for its part leads to an increased formation of new vessels in the area of the tumor. Accordingly, the TP correlates with fast malignoma growth, aggressive invasion behavior and a bad forecast (Folkman et al., 1996). This is why precisely such patients with a bad forecast should profit from therapy with capecitabine.
Capecitabine has an additive effect with other cytotoxic substances. Examinations were able to show additive effects with CPT-11, Tomudex™ (Tomudex™ was previously a registered trademark of Imperial Chemical Industries PLC), Mitomycin C or Cyclophosphamide and supra-additive ones with Paclitaxel or Docetaxel. Synergetic effects exist between capecitabine and a radiation therapy. These effects were not observed under 5-FU and are to be put down to the up-regulation of the key enzyme in the capecitabine metabolism as a result of the aforementioned cytostatics, but also the radiation (Sawada et al., 1998, 1999).
The drug capecitabine (brand name: Xeloda® (Xeloda® is a registered trademark of Hoffman-LaRoche Inc. for a pharmaceutical preparation, namely, an anticancer drug)) was registered in 2001 for therapy of a metastatic carcinoma of the large intestine. The year after, the drug was registered in combination with administration of Docetaxel (Taxotere® (Taxotere® is a registered trademark of Aventis Pharma S.A. for pharmaceutical preparations, namely, an anti-cancer preparation) for treatment of a metastatic mamma carcinoma. This was based on a clinical Phase III study, in which capecitabine was checked alone against Docetaxel in combination with Docetaxel (Taxotere®). For the first time, a significant extension of life for patients with metastatic breast cancer was achieved in this study. Although the effect of capecitabine as a so-called pro-drug chemotherapeutic is automatically bound to the existence of the enzyme thymidine phosphorylase, registration was granted without downstream proof. This also applies to all other fields of indication of capecitabine.
Results of Clinical Studies
Capecitabine was tested as a first, second and third line therapy in clinical studies on metastatic mamma carcinomas.
In a Phase II study (Blum et al., 1998), 162 patients with massive previous treatment and metastatic mamma carcinomas were given capecitabine in a dose of 2510 mg/m2/day for 14 days, followed by a 7-day therapy break. The treatment was continued in 3-week cycles.
The duration of the therapy was based on the sequence. Patients who reacted to the therapy with capecitabine were further treated until the tumor progress. An inclusion criterion was a primary or secondary resistance or a therapy failure in chemotherapy with Paclitaxel, 90% did not react to Anthracycline, 82% did not react to a therapy regime containing 5-FU.
46% had at least 2 or 3 previous therapies, 85 patients (53%) an adjuvant previous therapy with 5-FU. 89% of the patients treated had already received four or more cytotoxic substances.
An objective remission rate of 20% was observed in the “intend to treat” evaluation (162 patients) and confirmed by an independent commission. Three complete remissions observed lasted for 106, 109 and 194+ days.
43% of the patients profited thanks to a stable sequence of the illness. In a sub-group analysis, 42 of the anthracycline and paclitaxel therapy refractory patients again showed a reaction rate of 29%.
The mean remission duration was 241 days, the median time until progression 93 days and the median survival of 384 days was surprisingly long for these patients with intensive previous treatments.
Not only the anti-tumorous potency, but in particular the palliative effect, which is important for this group of patients with a view to pain reduction, was proven by the study for capecitabine. Of 51 patients who documented a pain figure above 20 mm at the start on the study on an analogue pain scale, the pain was reduced by more than 50% by the therapy in 47% of them.
The capecitabine therapy showed an excellent tolerability profile. No pre-medication or primary prophylaxis were necessary. Therapy-induced fatalities did not occur.
In a further phase II study, capecitabine was used in the second line in patients after anthracycline failure in comparison with Paclitaxel. 36% of the patients with capecitabine achieved an ORR, 21% overall response being achieved by Paclitaxel (O'Reilly et al., 1998). The study was ended prematurely after recruiting of 44 patients, as many patients had clear preferences with a view to their medication, either preferring Paclitaxel or an oral substance. Randomization was therefore difficult.
Under capecitabine and under Paclitaxel, a median reaction duration of 9.4 months was established. The median time until tumor progression was 3.0 months (92.5 days) for capecitabine and 3.1 months (95 days) for Paclitaxel.
Current data of a phase II study concluded with recruiting by Reichardt et al. on effectivity and tolerability of a capecitabine therapy of a metastatic mamma carcinoma following a previous therapy containing taxane were presented at the San Antonio Breast Cancer Symposium 2000. Up to now, 97 patients included in the study have been evaluable. Median age 55 years (range 36-77), median Karnofsky index 90% (range 60-100). 91% of the patients had previous therapy containing anthracycline, 100% containing taxane (51% Paclitaxel, 45% Docetaxel, 4% both taxanes).
Capecitabine was administered in a dose of 1250 mg/m2 twice a day, morning and evening, for 14 days followed by a 7-day break.
After an average of 4 cycles (range 1-15), 77 and 68 patients are evaluable for toxicity and effectivity respectively. Toxicity is mild with 40% hand and foot syndrome, nausea and vomiting 38%, diarrhea 21% and lethargy 18% CTC degree 1 and 2. Merely 14% developed a degree 3 hand and foot toxicity.
2 patients (3%) achieved a complete remission, 15 (22%) a partial one and 47% showed stabilization of the disease. All told, tumor control was achieved in 72% of the patients with intensive previous treatment (Reichardt et al, 2000).
In accordance with a phase III study (O'Shaughnessy J et al. Superior survival with capecitabine plus docetaxel combination therapy in anthracycline-pretreated patients with advanced breast cancer: phase III trial results. J Clin Oncol 20 2812-23 (2002), a distinct increase of the effect by combination therapy with capecitabine and Docetaxel compared with Docetaxel was observed in patients with a metastatic mamma carcinoma, but merely 42% of the tumors examined in the combination therapy showed a reaction to the treatment.
The disadvantage of the state of the art is that a high percentage of the patients does not react to the treatment with capecitabine or capecitabine in combination with taxanes. As capecitabine has been admitted without a downstream proof of thymidine phosphorylase, treatment is also given as a rule to insensitive or non-reactive patients with no kind of benefit from the therapy who are unnecessarily subjected to the undesirable effects without a therapeutic success occurring or being expected.
Therapies based on molecular biology are always highly selectively aimed at blocking certain cellular receptors or enzymes of the tumor cells. This is why their good effectivity, but also the low range of undesired effects compared with chemotherapy can be explained. Accordingly, detection of the estrogen and progesterone receptors is absolutely necessary for implementation of an anti-hormonal therapy. This applies in the same way to the implementation of a herceptin therapy. Here, detection of HER-2 by means of immuno-histochemistry (ICH) or fluorescence in situ hybridization (FISH) is necessary. The drugs Xeloda® (capecitabine), Celebrex® (celecoxib) (Celebrex® is a trademark of G.D. Searle LLC for pharmaceuticals in the nature of anti-inflammatory analgesics) and Avastin® (bevacizumab), which are also highly selective, were given their registration without downstream detection. Nevertheless, they can only develop their effect if the corresponding target substrate exists in the tumor tissue. This is why it appears necessary to bind the use of the drugs to the detection of the corresponding target substrates as well.